Method for making elastic yarn containing keratinous fibers



F. W. MARCO April 20, 1965 METHOD FOR MAKING ELASTIC YARN CONTAINING KERATINOUS FIBERS Filed May 29, 1962 2 Sheets-Sheet 1 FIG. I-

INVENTOR. FRANCIS W. MARCO ATTORNEY Apnl 20, 1965 F. w. MARCO 3,178,877

METHOD FOR MAKING ELAsTIc YARN CONTAINING KERATINOUS FIBERS Filed May 29, 1962 2 Sheets-Sheet 2 Apply 'twiSf on ke roiinous fiber coniaining yarn Wind iwisied yarn on perforated spin d le mmerse in reducing agent Drain and steam Remove a pplied 1wi sf INVENTOR. FRA NCIS w. MARCO AT ORNEY United States Patent C 3,178,877 METHOD FOR MAKING ELASTIC YARN CONTAINING KERATHNOUS FIBERS Francis W. Marco, Spartanburg, S.C., assignor to Deering Milliken Research Corporation, Spartanburg, S.C., a

corporation of Delaware Filed May 29, 1962, Ser. No. 195,601 7 Claims. (Cl. 57-157) This invention relates to an all textile yarn having elastic characteristics and more specifically to a method for making an all textile yarn containing keratinous fibers having extensibility and recovery properties.

Elastic yarns are well-known in the textile field. Elastic yarn of man-made polymeric fibers have been produced in a variety of forms, which have found wide acceptance. Naturally occurring fibers, however, have generally been limited to use as a cover material for yarns employing a man-made elastomeric core or to use as blends in manmade elastic monofilament yarns. Certain natural fibers, such as the keratinous fibers, have inherent properties of extensibility and recovery. The term keratinous fibers as used herein is meant to include any naturally occurring filamentary material or regenerated filamentary material containing a major proportion of corresponding long chain fibrous proteins. The development of extensibility and recovery properties of keratinous fibers, if of sufficient intensity could result in an elastic yarn, the elastic properties of which are provided by the keratinous fiber. It should be understood that the term elastic when used with reference to the yarn of this invention is meant to define a mechanical extensibility rather than a rubber-like condition.

An elastic yarn wherein the elasticity is provided by the fibers making up the yarn will usually have superior bulking qualities. A fiber which has the tendency to contract upon its own axis will, when spun into a yarn, have a tendency to extend at right angles to the longitudinal axis of the yarn, thereby giving the yarn bulking qualities. While all elastic yarns do not have bulking qualities, the coexistence of these two features is quite common.

It is, therefore, an object of this invention to provide an elastic yarn wherein the elasticity is furnished by keratinous fibers.

It is another object of this invention to provide a keratinous fiber containing blended elastic yarn wherein the elasticity is furnished by the keratinous fibers.

It is a further object of this invention to provide a bulked keratinous yarn.

It is still another object of this invention to provide a keratinous fiber containing blended bulked yarn.

I have now discovered that it is possible to impart increased elastic recovery properties to the keratinous fibers of a preformed yarn, by imposing a twist on the yarn containing keratinous fibers, setting the imposed twist and then untwisting the yarn so that at least all of the imposed twist is removed. The twist is preferably set by means of a reducing agent capable of splitting the characteristic cystine linkage although a temporary setting may be obtained by the use of steam. The yarn employed may be a yarn consisting entirely of keratinous fibers, or may be a blended yarn containing less than 100% but more than 50% of keratinous fibers with the remainder of the blend being either man-made or naturally-occurring non-kerati nous fibers. Specific keratinous fibers which are suitable for purposes of this invention are fibers such as, for instance, sheepwool, lambwool, mohair, camelhair, alpaca, cashmere, vicuna, llama, angora wool and the like.

Any reducing agent capable of rupturing the desired level of the disulfide linkages is suitable for use in accordance with this invention. Among the suitable reducing agents there are included lower alkanolamine sulfites, such as monoethanolamine sulfite and ispropanolamine sulfite, and others containing up to about 8 carbon atoms in the alkyl chain, such as n-propanolamine sulfite, n-butanolamine sulfite, dimethylbutanolamine sulfite, dimethylheranolamine sulfite and the like; metallic formaldehyde sulfoxylates, such as Zinc formaldehyde sulfoxylate, the alkali metal sulfoxylates, such as sodium formaldehyde sulfoxylate; the alkali metal borohydrides, such as sodium borohydride, potassium borohydride and sodium potas sium borohydride; alkali metal sulfites, such as sodium or potassium bisulfite, sulfite, metabisulfite, or hydrosulfite; ammonium bisulfite, sodium sulfide, sodium hydrosulfide, cysteine hydrochloride, sodium hypophosphite; sodium thiosulfate, sodium dithionate; titanous chloride; sulfurous acid; mercaptan acids, such as thioglycollic acid and its water-soluble salts, such as sodium, potassium or ammonium thioglycolate; mercaptans, such as hydrogen sulfide, and sodium or potassium hydrosulfide; alkyl mercaptans, such as butyl or ethyl mercaptans and mercaptan glycols, such as 3-mercapto ethanol; and mixtures of the reducing agents.

Beneficial results are often obtained if the reducing agent is employed in conjunction with a swelling agent of a low molecular weight polyhydroxy compound. Urea constitutes the most readily available and desirable swelling agent, although any other material which will swell wool fibers in an aqueous medium is suitable. For example, guanidine compounds such as the hydrochloride; formamide, N,N-dimethylformamide, .acetamide, thiourea, phenol, lithium salts, such as the chloride, bromide, and iodide and the like are similarly useful.

By the term low molecular weight polyhydroxy compound is meant a compound containing more than one hydroxy group and having a molecular weight no greater than about 4000. Of these compounds, the most readily available and desirable compound, from the standpoint of ease of application, comprises ethylene glycol. A particularly preferred group of glycols includes the polyfunctional glycols having terminal hydroxyl groups separated by 2 to 10 methylene groups, including, of course, the preferred ethylene glycol as well as trimethylene glycol, tetramethylene glycol, pentame-thylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol, nonamethylene glycol, and decamethylene glycol, or such glycols as 1,2-propylene glycol, dipropylene glycol, 1,3- butylene glycol, diethylene glycol, polyethylene glycol or the like.

Polyfunctional compounds containing more than 2 hydroxyl groups include the polyfunctional alcohol glycerols The reducing agent with or without the swelling agent or polyhydroxy compound may be applied to the fabric in any desired amount, depending upon the degree of reducing desired. In general, optimum results are obtained when aqueous solutions containing from about 0.01 to about 20% by weight and most preferably from 2 to about 10% by weight of the reducing agent is applied to the yarn. The swelling agent or polyhdroxy compound if employed may be applied tothe yarn by addition to the aqueous solution of reducing agent of amounts of from about 3 to about 50% and most preferably from about 5 to about 20% by weight. Higher concentrations may be utilized where the yarn is to be exposed to the treating medium for only a short time or where the method of applying the reagents necessitates, e.g., when the reagents are applied by techniques other-than by immersion in an aqueous medium containing the reagents.

The reducing agent which splits the cystine linkage of keratinous fibers does not produce a permanent split. The-split linkages are easily reoxidized, by operations site direction to the twist in the single yarn. In the former case, a' hard yarn is obtained, and in the latter case, a soft yarn is produced. The result may be explained by the fact that the initial imposed twist. is only placed in the yarn temporarily, and that after setting the yarn in'this configuration, the imposed twist is taken out, and an additional twist may be placed in the opposite direction'so that in fact the resulting twist may be opposite to the initial imposed twist. An additional factor is that in a plied yarn each singles yarn may have ditferent twist direction and different twist levels. When different 7 twist directions and different twist levels are present in 7 whether a helical .or a random curling elfect is produced.

such as, for instance, atmospheric exposure, to reform the disulfide bonds. While the keratinous fiber remains substantially unchanged chemically by the reduction and oxidation operation, a physical reformation of the cystine .linkage takes place probably with some changes in hydrogen bonding which will under proper conditions produce a reformed fiber with an elastic memory. Elastic memory is the feature which gives the individual keratinous fibers of this invention their extensibility and recovery properties. The extensibility and recovery properties of'the keratinous fibers of this invention should For instance, in a 4/27s worsted yarn at low imposed twist levels (e.g., about 5-14 t.p.i.) the helical form predominates while at higher. imposed twist levels(e.g., about 1630 t.p.i.) a random effect is obtained. More specifically, the helical form may be characterized by a twist multiple of less than about 4.5 while the random form may be characterized by a twist multiple of greater than about 4.5. Twist multiple may be defined as imposed turns per centimeter squared times grex divided by 10 to the 4th power.

The drawings comprise illustrations (enlarged three times) of the yarnsof 'thisjinvention and a flow sheet illustrative of the process of this invention.

' FIGURE 1 is illustrative of the helical yarn of this invention. I

FIGURE 2 is illustrative of the random yarn of this invention. 7

not be confused with the rubber-like condition of a fiber whose polymeric structure has been extensively degraded. The process can be applied to any'yarn ply or any yarn consisting of a plurality of plies, the only limiting and may be dyed or scoured at this point, after Which the yarn is dried. The final operation is to untwistthe' V yarn so that all the imposed twist is removed, and depending upon the effect desired, a few turns of the opposite twist may be placed in the yarn.

' The elasticized yarn obtained by the process of this invention and consisting wholly or partially of kerati nous fibers may then be plied with other elasticized yarns consisting wholly or partially of keratinous fibers or may be plied with nonelastic yarns consisting wholly or par-.

tially of keratinous fibers or may be plied with nonelastic The yarn of FIGURE 1 is an all wool elastic yarn prepared according to this invention. The yarn of FIG- URE 1 has a twist multiple of less than about 4.5 and has a helical configuration. The helical configuration may be described as a yarn ply or a plurality of yarn plies extending in a helical spiral along the longitudinal axis of the yarn. The ability, of the helical spiral to extend and contract allows; the yarn to achieve an elastic effect. The yarn of FIGURE 2 has a twist multiple greater than about 4.5 and has a random configuration. The random configuration may be described as a yarn ply or plurality of plies having coils, loops and whorls at random intervals along the length of the individual plies. In a plied yarn of random configuration, the individual plies may have, at certainintervals along the yarn length, a similar configuration or a dissimilar configuration. The random configuration yarn achieves its elasticity by the ability of. the coils, loops and whorls to extend under tension and then to contract to their original configuration upon removal of the tension.

5 FIGURE 3 is a flow sheet which'illustrates in a step: wise manner the process of this invention.

As previously stated, the finished yarn may contain fibers otherthan 'keratinous fibers. These fibers may be present as a blend in the keratinous,fiberrcontaining plies prior to elastici zing treatment or may be present as a homogeneous non-keratinous' ply which is twisted with the. keratinous fiber-containing ply subsequent to elasticizing operations on the keratinous fiber-containing ply.

The non-keratinous fibers may be fibers such as, for instance, cellulosics, such as cotton, rayon, cellulose acetate, cellulose triacetate, vinyl fibers, acrylic fibers, polyyarns consisting of non-keratinous natural fibers, syn- V thetiefibers and mixtures thereof. By varying the type of plies twisted into the finished yarn, a variety of yarns having various elastic and bulking characteristics may be obtained. V

In performing the elasticizing operation, there area number of possible approaches. .ing may be either in the same direction or in the oppo- First, the initialtwistamidefibers, polyester fibers and the like. Regardless of how the non-keratinous fibers are blended into the finished yarn the only elasticizing effect is that furnished by the keratinous fibers. The non-keratinous fibers, however, furnish substantial bulk to the finishedyarn. The

"shrinkage. of the keratinous fibrous elements'tends to crimp, loop and pucker the non-keratinous fibers, thereby furnishing bulk to the finished yarn.

Bulk measurements were made on the yarns of this invention by the following process:

A skein of yarn was placed in a slot in a metal block. The base of the slot is 2 x 5 cm., and the height is 3 cm. A plunger which was fitted to the slot was then connected to the cross-head of an Instron machine, and a block containing the yarn was placed on the compression cell. The plunger was then pressed against the yarn in the slot and a measurement was taken on the third compression cycle. The bulk specific volume of any yarn can be determined at any pressure by knowing the weight of the yarn contained in the slot and the volume which it occupied. The same procedure was employed on knitted fabrics except that the slot was not necessary in that the knit retained its own shape, and only a plunger was employed.

The results of this test are given in the following table, designated as Table I:

1 The yarn used in this case is a 1/27s worsted yarn containing 14 Z. The twist in the control yarn refers to the twist actually left in the finished yarn, while the twist noted in the elasticized yarn refers to the imposed twist placed in the yarn before untwisting. The imposed twist was set by the same method used for the yarns of Table I. The knit fabric was prepared by the same method used for the fabrics of Table I.

TABLE I Results from bulk compression tests on yarn and fabric Yarn 1 Knit fabric 2 Bulk compression (3rd cycle) 4/275 3.5 4/27s 3.5 4/27s 5 T 4/275 10 T 4/275 3.5 4/27s 3.5 4/275 5 T 4/27s 10 T 3 control T Z clas. 2 elas. Z elas. T 8 control T Z clas. Z elas. T Z elas.

a Pressure 10 gjem. 12. 12. 57 13. 10 14. 16 7. l8 7. 86 7. 66 7. 58 E bi, 20 gJcm. 10.30 10. 60 11.20 12. 20 6. 7. 04 6.83 6. 85 Few 28 g./cm. 7. 94 8.00 8. 54 9. 23 5. 30 5. 75 5. 21 5. 74 100 g./em. 6. 42 6. 29 6. 73 7. 16 4. 41 4. 73 4. 61 4. 85 m 180 g./cm. 5. 23 5. 03 5. 39 5. 68 3. 71 3. 97 3.85 4. l2

1 The yarn used in this case is a 1/27s worsted yarn containing 8 Z.

left in the finished yarn, while the twist noted in the The twist in the control yarn refers to the twist actually elasticized yarn refers to the imposed twist placed in the yarn before untwisting.

The imposed twist was set in the elasticized yarn by winding the yarn around a perforated dye spindle, immersing in an aqueous solution of 1% sodium bisultlte and 0.02% ing. The yarn was then nntwisted to 3.5 turns 8 twist.

2 The knit fabric was prepared on a circular knitting machine using a jersey stitch, the

17 and a wale count of 10.

Extension-cycling tests were performed on the elasticized yarns of this invention and on the fabrics woven from the elasticized yarns of this invention. The tests are carried out by locking the section of yarn or fabric in the jaws of the Instron testing machine. The secured sample was then loaded with the weight of 0.01 grn./grex. The load was then removed and the procedure repeated for two additional cycles. On completing the third cycle, measurements were taken to determine extensibility and elastic recovery. Extensibility may be defined as the ability of a material to return spontaneously to its former size, shape or attitude after being strained. Elastic recovery may be defined as the ratio of elastic extension to total extension. The results of the tests carried out on yarn are given in the table designated as Table Ii. The results of the tests carried out on the knit fabric are given in the table designated as Table III.

TABLE II Results from yarn extension-cycling tests Elastic recovery (percent) 3rd cycle bility Yarn 1 (percent) 1 The yarn used in this case is a l/27s worsted yarn containing 14 Z. The twist in the control yarn refers to the twist actually left in the finished yarn, while the twist noted in the elasticized yarn refers to the imposed twist placed in the yarn before untwisting. The imposed twist was set in the elasticized yarn by winding the yarn around a perforated dye spindle, immersing in an aqueous solution of 1% sodium bisullite and 0.02% wetting agent, steaming for 10 minutes, washing in cold water for 10 minutes and then drying. The yarn was then untwistcd to 3.5 turns S twist.

wetting agent, steaming for 10 minutes, washing in cold water for 10 minutes and then dryfinished fabric having a course count of The elastic properties of the yarn of this invention are quite durable. It has been found that the elasticized yarns of this invention will tolerate steaming and mild soaping while in the relaxed form. The elasticized yarn, when stretched and placed on a bobbin for an extended period of time, has relatively little tendency to retract on being relaxed, but upon steaming or Wetting the elasticity of the yarn is immediately realized. This phenomenon is an asset, since knitting in this stretched state will be much less troublesome than knitting a yarn which tends to contract. For example, a fabric may be knitted and then steamed to produce a bulky fabric.

The various embodiments of this invention will be readily seen from the following examples. The examples, however, are given for purposes of illustration and should not be considered as limiting the spirit or scope of this invention.

EXAMPLE I Four ends of single 27s yarn having 14 turns of S twist per inch in each end are plied and twisted to 10 turns of Z twist. The plied yarn is then wound onto a perforated dye spindle so that it retains the 10 turns of Z twist. The spindle is then immersed in an aqueous solution containing 1% of sodium bisulfite. After about 10 minutes, the excess sodium 'bisillfite solution is drained from the package and steam is then passed through the spindle for 10 minutes. After rinsing in tap water and drying in an oven at C., the yarn is untwisted onto another bobbin at 18.9 turns of S twist, so that the yarn now has 8.9 turns of S twist. (There is a small less in S twist due to differences in the length of the yarn during the treatment.)

The yarn is then knit into a sweater body, steamed for 5 minutes at 0 p.s.i. and dried in a relaxed state. The resulting knit fabric is characterized by a more uniform fabric knit from untreated plied yarns, thereby essentially eliminating the bagginess and other deformation which f mgn occurs in the normal wearing of sweaters prepared from untreated yarn. 7 7

EXAMPLE II 7 of 8 twist. The resulting yarn is wound onto a bobbin and set as in Example I and then untwisted onto another bobbin with 25.4 turns of Z twist. Whereas the yarn of Example I is characterized by a substantially uniform helical configuration, the yarn of this example is" characterized by a high degree of bulk due to the random displacement of loops and kinks along the length of the yarn. In addition, this yarn is characterized by' a low value of total twist which enhances the bulking effect. After knitting, as in Example I, the resulting fabric is characterized by a greater degree of elasticity. In addition, due to the increased bulk of the yarn the knitting stitch is nearly obscured, presenting a pleasing appearance and providing a pleasant hand.

EXAMPLE III A single end of single 27s wool yarn having an original twist of 14 turns of Z twist per inch is twistedfto 25 turns of Z twist per inch, set with sodium bisulfite as in Example I at the 25 turn per inch level and untwisted back to 14 turns per inch. A single end of single 27s cotton yarn having an original twist of 14 turns per inch is then plied and twisted with the treated wool yarn to 10 EXAMPLE IV Four ends of single 27s yarn consisting of 50% wool and 50% cotton having 14 turns per inch of S twist in each end are plied and twisted to 10 turns of Z twist. The plied yarn is then wound onto a perforated dye spindle, so that it retains the 10 turns of Z twist. The

spindle is then immersed in a solution containing 1% of thioglycollic acid. After about 10 minutes, excess thioer body, steamed for 5 minutes at 0 p.s.i. and dried in a relaxed state. The resulting knit fabric is characterized by a more uniform knit structure and by high bulk- I EXAMPLE VI One end'of single and one end of single 27s mohair yarn having a Z twist are plied and twisted to 15 turns of Z twist. .The plied yarn is then wound ontoa perforated dye spindle and immersed in a solutioncontaining 1% of sodium bisulfite. After about 10 minutes, excesssodium bisulfite solution is drained from the package and steam is passed through the spindle for about 10 minutes. rinsed with water and dried in an oven at about 80 C. The yarn is then unwound onto another bobbin to 20 turns per. inch of S twist. The. finished yarn, when knitted into a fabric is characterized by a high degree of elasticity and bulk.

EXAMPLE VII One end of'single 27s mohair yarn having an S twist and one endof single 27s mohair yarn having a Z twist are plied and twisted to 15 turns of S twist. The plied yarn is then wound onto a perforated .dye spindle, so that it retains the 15 turns of S twist. The spindle is then immersed in a solution containing 1% of sodium bisulfite. After aboutlO minutes, the excess sodium bisulfite solution is drained from the package and steamis passed through the spindle for a period of about 10 minutes.

The spindle is then rinsed in water and dried in an oven at about 80 C. Theyarn isthen" unwound onto another bobbin'so that 20 turns of Z twist will remain in the finished product. When the finished yarn is knitted into a fabric, the fabric is characterized by a high degree of elasticity and bulking.

EXAMPLE VIII One end oftl/27s wool yarn having an S twist and one end of 1/27s wool yarn also having an S twist are plied and twisted to 15 turns of Z'twist. The plied yarn is then wound onto a perforated dye spindle so that it retains the 15 turns of Z twist. The spindle is then immersed in a solution containing 1% of sodium bisulfite. After about 10 minutes the excess sodium bisulfite solution is drained from the package and steamed and passed glycollic acid is drained from the package and steam is passed through a spindle for a period of about 10 minutes. rinsed and dried in an oven 'at about 80 C. The yarn is untwisted onto another bobbin at 18.9 turns of S twist, so that the yarn has 8.9 turns'of S twist. The yarn is then knit into'a sweaterbody, steamed for 5 minutes at O p.s.i. and dried in a relaxed state. fabric is characterized by a more uniform knit structure and also by high-bulking characteristics.

' EXAMPLE v The yarn carried on the dye spindle is'again The resulting knit through the spindle for .a period of about 10 minutes. The spindle is then rinsedin water and dried in an oven at about 80 C. The yarn is then Wound onto another degree of elasticity and bulking.

EXAMPLE IX Two ends of 1/27s Woolyarn, each having an S twist are plied and twisted to 15 turns of S twist. The plied yarn is then wound onto a. perforated dye spindle so,

that it retains the, '15 turns of S twist. The spindle is then immersed in a solution containing 1% of sodium onto a perforated dye spindle and the spindle is immersed A in a solution containing 1% of 2-mercaptoethanol. After about 10 minutes, excess Z-mercaptoethanol solution is drained from the package and steam is passed through" the spindle for a period of about 10 minutes. The yarnwound spindle is then rinsed in water and dried in'an oven at about 80 C. The yarn is then untwisted onto originals twist remains. Three ends of the single 27s 'wool yarn treated according to the preceding process are r minutes.

bisulfite. After about 10 minutes, the excess sodium bisulfite solution is drained from the package and steam is passed through the spindle for a period of about 10 The 'spindle is then rinsed in water and dried inan oven at about 8 0"v C. The yarn is then wound onto another bobbin in a manner such that 7 turns of Z twist remain in the finished product. When the finished yarn is knitted into a fabric, the fabric is characterized'by a soft hand and a high degre'e of elasticity and bulking. The knit pattern of the resultant'knit fabric has a pleasing uniform appearance.

EXAMPLE X One end of 1/27s wool yarn having an S twist, one end of1/27s wool yarn alsohaving an S twist and one end of 1/27s wool yarn having a Z twist are plied and twisted to 15 turns of Z twist. The plied yarn is then 27s mohair yarn having an S twist The spindle is thenwound onto a perforated dye spindle so that it retains 15 turns of Z twist. The spindle is then immersed in a solution containing 1% of sodium bisulfite. After about 10 minutes, the excess sodium bisulfite solution is drained from the package and steam is passed through the spindle for a period of about 10 minutes. The spindle is then rinsed in water and dried in an oven at about 80 C. The yarn is then wound onto another bobbin in a manner such that 5 turns of S twist remains in the finished product. When the finished yarn is knitted into a fabric, the fabric is characterized by a high degree of elasticity and bulking. The resultant knit fabric is characterized by a hard resilient hand.

EXAMPLE XI One end of l/27s wool yarn having an S twist, one end of 1/27s wool yarn also having an S twist and one end of 1/27s wool yarn having a Z twist are plied and twisted to 15 turns of S twist. The plied yarn is then wound onto a perforated dye spindle so that it retains the 15 turns of S twist. The spindle is immersed in a solution containing 1% of sodium bisulfite. After about minutes, the excess sodium bisulfite solution is drained from the package and steam is passed through the spindle for a period of about 10 minutes. The spindle is then rinsed in water and dried in an oven at about 80 C. The yarn is then unwound onto another bobbin in a manner such that 5 turns of Z twist remain in the finished product. The finished yarn is characterized by a high degree of elasticity and bulking. The resultant knit fabric is characterized by a soft resilient hand.

EXAMPLE XII Three ends of 1/27s wool yarn having an S twist are plied and twisted in turns of Z twist. The plied yarn is then wound onto a perforated spindle so that it retains the 15 turns of Z twist. The twist is then set in the yarn by the same manner disclosed in Example XI. The said yarn is then unwound onto another bob-bin in a manner such that 7 turns of S twist remained in the finished product. The finished yarn is characterized by a high degree of elasticity and bulking.

EXAMPLE XIII Three ends of 1/ 27s Wool yarn having a Z twist are plied and twisted to 15 turns of S twist. The plied yarn is then wound onto a perforated dye spindle in a manner such as to retain the 15 turns of S twist. The 15 turns of S twist are then set in the yarn by the method disclosed in Example XI. The twist set yarn is then wound onto another bobbin in a manner such that 5 turns of Z twist remain in the finished product. The finished yarn was characterized by having a high degree of elasticity and bulking.

EXAMPLE XIV Four ends of single 27s wool yarn having 14 turns per inch of S twist in each end are plied and twisted to 10 turns of Z twist. The plied yarn is then wound onto a perforated dye spindle so that it retains the 10 turns of Z twist. The spindle is then immersed in a solution containing 2% thioglycollic acid and 2% ethylene glycol. After about 10 minutes, excess solution is drained from the package and steam is passed through a spindle for a period of about 10 minutes. The yarn carried on the dye spindle is again rinsed and dried in an oven at about 80 C. The yarn is untwisted onto another bobbin at 18.9 turns of S twist so that the yarn has 8.9 turns of S twist. The finished yarn is characterized by a high degree of elasticity and bulking.

EXAMPLE XV Four ends of single 27s Wool yarn having 2 twist are plied and twisted to 10 turns per inch of Z twist. The plied yarn is then wound onto a perforated dye spindle so that it retains the 10 turns of Z twist. The spindle is then immersed in an aqueous solution containing 2% of soi0 dium bisulfi-te and 0.02% of wetting agent. After about 10 minutes, the excess sodium 'bisulfite solution is drained from the package and steam is then passed through the spindle for 10 minutes, After rinsing in tap water and drying in an oven at C., the yarn is untwisted onto another bobbin at 18.9 turns of S twist so that the yarn has 6.98 turns of S twist (a loss of S twist is experienced due to variations in yarn length during treatment). The yarn is characterized by a helical configuration having a twist multiple of less than about 4.5 and a high degree of elasticity.

EXAMPLE XVI Four ends of single 27s wool yarn having Z twist are plied and twisted to 20 turns per inch of S twist. The plied yarn is then wound onto a perforated dye spindle so that it retains the 20 turns of S twist. The spindle is then immersed in an aqueous solution containing 2% of sodium bisulfite and 0.02% of wetting agent. After about 10 minutes, the excess sodium bisulfite solution is drained from the package and steam is then passed through the spindle for 10 minutes. After rinsing in tap water and drying in an oven at 80 C., the yarn is untwisted onto another bobbin at 25.4 turns of Z twist so that the yarn has 0.65 turn of Z twist (a loss of Z twist is experienced due to variations in yarn length during treatment). The yarn is characterized by a random configuration having a twist multiple greater than about 4.5 and a high degree of elasticity.

Having thus disclosed my invention, what I claim is:

1. A method for the preparation of an elastic yarn comprising imposing a twist on a yarn containing at least some keratinous fibers, durably setting the imposed twist by means of treatment with a reducing agent under conditions insuificient to cause extensive degradation of the polymeric structure of the keratinous fibers and then substantially untwisting the imposed twist.

2. A method for the preparation of a helical elastic yarn comprising imposing a twist on a yarn containing at least some keratinous fibers, durably setting the imposed twist by treatment with a reducing agent under conditions insuflicient to cause extensive degradation of the polymeric structure of the keratinous fibers and then untwisting the imposed twist, said imposed twisting operations being carried out in a manner such that the imposed twisted yarn has a twist multiple of less than about 4.5.

3. The method of claim 2 wherein said yarn is an allkeratinous yarn.

4. A method for the preparation of a random elastic yarn comprising imposing a twist on a yarn containing at least some keratinous fibers, durably setting the imposed twist by means of treatment with a reducing agent under conditions insufficient to cause extensive degradation of the polymeric structure of the keratinous fibers and then untwisting the imposed twist, said imposed twisting operations being carried out in a manner such that the imposed twisted yarn has a twist multiple greater than about 4.5.

5. A method for the preparation of an elastic yarn comprising plying together a keratinous fiber yarn with a non-keratinous fiber yarn, said keratinous fiber yarn being elasticized by imposing a twist, durably setting the imposed twist by means of treatment with a reducing agent under conditions insufficient to cause extensive polymeric degradation of the keratinous fiber and then substantially untwisting the imposed twist.

6. A method for the preparation of an elastic yarn comprising imposing a twist on a yarn containing at least some keratinous fibers, durably setting the imposed twist by means of treatment with a reducing agent under conditions insutficient to cause extensive degradation of the polymeric structure of the keratinous fibers, untwisting the imposed twist and adding twist in the direction opposite imposed twist.

7. A method for the preparation of an elastic yarn comprising plying together a keratinous fiber yarn with a non-keratinous fiber yarn, said keratinous fiber yarn being elasticized by imposing a twist, durably setting the. f 2,662,560 12/53 Jackson 57--156 X imposed twist by means of tireatmen t with a medu'cing 2,723,213 11/55 Powers 57153 X agent under conciition s insuificient to cause exte isive pol- 2 395 7 5 i' OConnell 57 164 X yr neric degradation of the keratmous fiber; untwistmg 3,069,338 12/62 Wanays 57 V157 the imposed twistand adding twist in the direction oppo 5 V V v site the imposed twist. r F RE PATENTS l 1,246,006 10/60 France. References Cited by the Examiner 787,167 12/57, Great Britain UNITED STATI'ES PATENTS 10 I V W OTHER REFERENCES. p igggggg 5: 3:2 "H ly and Feughelman: Textile Research Journal, voi- 2019185 10/35 Kagi 57 157 X ume XXVII, No 12, December 1 95 7;vpages 919-924;art1- 1 10741 5; ;f ele entltled, Appl cationrof stetist cal Theory of E lasto- 25O9347 5/50 Jackson "f mers no Supercontracted Keratin Flbers.

7 7 2,615,782 2%? Haefele 8128 MERVIN STEIN, Primary Examiner.

2,642,332 Cohen 57-46 4 X 

1. A METHOD FOR THE PREPARATION OF AN ELASTIC YARN COMPRISING INPOSING A TWIST ON A YARN CONTAINING AT LEAST SOME KERATINOUS FIBERS,DURABLY SETTING THE IMPOSED TWIST BY MEANS OF TREATMENT WITH A REDUCING AGENT UNDER CONDITIONS INSUFFICIENT TO CAUSE EXTENSIVE DEGRADATION OF THE POLYMERIC STRUCTURE OF THE KERATINOUS FIBERS AND THEN SUBSTANTIALLY UNTWISTING THE IMPOSED TWIST. 